# Physics Question MoleculesWatch

Announcements
This discussion is closed.
#1
I have a question that I can't solve. Could someone tell me the right answer along with how they obtained it?

Q - The densities of water and steam are 1.0 X 10^3 kg/m3 and 6.1 X 10^-1 kg/m3 respectively.

What is the ratio: (Average seperation of steam molecules)/(Average seperation of water molecules) ?

A- 12 B- 40 C- 250 D- 1000
0
14 years ago
#2
as a water molecule has the same mass as a steam molecule, you can say the mole density (molecules per volume) is the same.

so in one metre cubed there are x molecules of water and y molecules of steam, where
y/x = 6.1*10^-1 / 1*10^3 = 6.1*10^-4

however we want to convert to a length from a volume, so we find the cube root:
cube root = 0.08480
the inverse of this is 11.7 or something, close enough for my liking to 12.
0
X
new posts
Back
to top
Latest
My Feed

### Oops, nobody has postedin the last few hours.

Why not re-start the conversation?

see more

### See more of what you like onThe Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

### University open days

• University of East Anglia
Sun, 20 Oct '19
• University for the Creative Arts
Sun, 20 Oct '19
• University of Gloucestershire
Sun, 20 Oct '19

### Poll

Join the discussion

Yes I know where I'm applying (65)
65.66%
No I haven't decided yet (21)
21.21%
Yes but I might change my mind (13)
13.13%